import { TupleKey } from '../types/TupleKey';
import {
  Listener,
  NotificationEvent,
  NotificationLookupArguments,
  NotificationRepository,
  ScheduledNotification
} from "./NotificationRepository";
import { createClient } from "redis";

export class RedisNotificationRepository implements NotificationRepository {
  private listeners: Listener[] = [];
  private readonly NOTIFICATION_KEY_PREFIX = 'notification:';

  constructor(
    private redisClient = createClient({
      url: process.env.REDIS_URL,
      socket: {
          tls: (process.env.REDIS_URL?.match(/rediss:/) != null),
          rejectUnauthorized: false,
      }
    }),
  ) {
    this.getAllNotificationsForShuttleAndStopId = this.getAllNotificationsForShuttleAndStopId.bind(this);
    this.getSecondsThresholdForNotificationIfExists = this.getSecondsThresholdForNotificationIfExists.bind(this);
    this.deleteNotificationIfExists = this.deleteNotificationIfExists.bind(this);
    this.addOrUpdateNotification = this.addOrUpdateNotification.bind(this);
    this.isNotificationScheduled = this.isNotificationScheduled.bind(this);
    this.subscribeToNotificationChanges = this.subscribeToNotificationChanges.bind(this);
    this.unsubscribeFromNotificationChanges = this.unsubscribeFromNotificationChanges.bind(this);
  }

  get isReady() {
    return this.redisClient.isReady;
  }

  public async connect() {
    await this.redisClient.connect();
  }

  public async disconnect() {
    await this.redisClient.disconnect();
  }

  public async clearAllData() {
    await this.redisClient.flushAll();
  }

  private getNotificationKey(shuttleId: string, stopId: string): string {
    const tuple = new TupleKey(shuttleId, stopId);
    return `${this.NOTIFICATION_KEY_PREFIX}${tuple.toString()}`;
  }

  public async addOrUpdateNotification(notification: ScheduledNotification): Promise<void> {
    const { shuttleId, stopId, deviceId, secondsThreshold } = notification;
    const key = this.getNotificationKey(shuttleId, stopId);

    await this.redisClient.hSet(key, deviceId, secondsThreshold.toString());

    this.listeners.forEach((listener: Listener) => {
      const event: NotificationEvent = {
        event: 'addOrUpdate',
        notification
      };
      listener(event);
    });
  }

  public async deleteNotificationIfExists(lookupArguments: NotificationLookupArguments): Promise<void> {
    const { shuttleId, stopId, deviceId } = lookupArguments;
    const key = this.getNotificationKey(shuttleId, stopId);

    const secondsThreshold = await this.redisClient.hGet(key, deviceId);
    if (secondsThreshold) {
      await this.redisClient.hDel(key, deviceId);

      // Check if hash is empty and delete it if so
      const remainingFields = await this.redisClient.hLen(key);
      if (remainingFields === 0) {
        await this.redisClient.del(key);
      }

      this.listeners.forEach((listener) => {
        const event: NotificationEvent = {
          event: 'delete',
          notification: {
            deviceId,
            shuttleId,
            stopId,
            secondsThreshold: parseInt(secondsThreshold)
          }
        };
        listener(event);
      });
    }
  }

  public async getAllNotificationsForShuttleAndStopId(
    shuttleId: string,
    stopId: string
  ): Promise<ScheduledNotification[]> {
    const key = this.getNotificationKey(shuttleId, stopId);
    const allNotifications = await this.redisClient.hGetAll(key);

    return Object.entries(allNotifications).map(([deviceId, secondsThreshold]) => ({
      shuttleId,
      stopId,
      deviceId,
      secondsThreshold: parseInt(secondsThreshold)
    }));
  }

  public async getSecondsThresholdForNotificationIfExists(
    lookupArguments: NotificationLookupArguments
  ): Promise<number | null> {
    const { shuttleId, stopId, deviceId } = lookupArguments;
    const key = this.getNotificationKey(shuttleId, stopId);

    const threshold = await this.redisClient.hGet(key, deviceId);
    return threshold ? parseInt(threshold) : null;
  }

  public async isNotificationScheduled(
    lookupArguments: NotificationLookupArguments
  ): Promise<boolean> {
    const threshold = await this.getSecondsThresholdForNotificationIfExists(lookupArguments);
    return threshold !== null;
  }

  public subscribeToNotificationChanges(listener: Listener): void {
    const index = this.listeners.findIndex(
      (existingListener) => existingListener === listener
    );
    if (index < 0) {
      this.listeners.push(listener);
    }
  }

  public unsubscribeFromNotificationChanges(listener: Listener): void {
    const index = this.listeners.findIndex(
      (existingListener) => existingListener === listener
    );
    if (index >= 0) {
      this.listeners.splice(index, 1);
    }
  }
}